"One of the questions I ask is with the up close shot of the man hitting the sheep, which is obviously exceptional and cruel and in many instances would be immediate dismissal, where exactly was the camera?" he said.

"Did the person know that they were filmed? Were they actually part of the process? There are lots of questions that need to be asked."

The release of the footage marks PETA's return to lobbying for the end of Australia's $2 billion per year wool industry.

The RSPCA and the Victorian Department of Primary Industries have confirmed to the ABC that complaints were filed by PETA last night, just hours before American news network NBC published a story about PETA's investigation.

PETA criticised for holding onto footage for a year

The animal rights group has also been sitting on some of the footage for about a year, saying all the video was filmed sometime in the past 12 months.

Ms Fryer was asked by the ABC why PETA did not file the complaints as soon as it found evidence of apparent wrongdoing.

"Well, as I say, there were those onsite who had the power to stop these abuses immediately but in order for authorities to act they do need a strong case," she replied.

The RSPCA says it will investigate the footage but it would not comment on how much harder it is when complaints are received so long after an alleged incident.

But Geoff Fisken, the president of the national representative body for wool growers, WoolProducers, says the delay will no doubt make investigations harder.

"If they really cared about the animals, I mean, the sooner that we got to the bottom of this and stopped it happening, the better," he said.

"I think the industry, like I say, doesn't condone this sort of behaviour and we would like to think that if it did happen it would be reported as soon as it happens."